Adolph a



1rcccdes 11 thcy i ii mi? showing `tiic .'coiistructicnand arrangement i s nt the nmgncticfpoleupleccSg:sandf- Fig. f 5v shows u si' l lul'poscly exaggerated lin order tm1x-niker flfhc, 1,d-i'zmings Knife vthcrc faire?A notl to he? taken as shop di'awings with accuratcddimcnsions. `r Such :details gnircmrehigzitccl to] lthe;` mechanic.

ledff m Comp' 1miv hardness@ VfyS msgiil rt 1 miki?? detailed (18- -pieces P.

cated as a whole by M. This magnet, which is preferably of the permanent steel type,

is U-shaped and closely follows the rectangular outline of the easing, so as to secure a maximum length of magnet in asmall' space. For convenience, the magnet is here shown as secured to the back wall 1 of the casing by means of screws 10. 'To the polar ends of magnet M aresecured a pair of pole The construction' and shape-0f these pole pieces is best shown in Fig. 4, where it will be seen that each pole piece comprises a pair of limbs 11 and l12. vThe llimbs 12 are straight extensions in axial alignment and separated to provide'an airgap 13. The llmbs 11 project forwardly and terminate in aligned polar faces 14. Each pole piece may be formed at the rear with a downwardly extending liange 15 arranged to lie flat against the body of the magnetand to receive a fastening screw 16. Additional screws 17 pass through the polar extensions 12 downwardly into the magnet. ln 'this "Way, the pole pieces P are rigidly secured to the body of the magnet. In order to facilitatev the assembling and adjustment of the V pole pieces l), they are vpreferably connected `.by a non-magnetic plate 18, which is fastened to the limbs 1l by screws 19 arranged to enter holes 20 'in the pole pieces. By providing the underside of plate 18 with lugs 21 arranged to engage the sides 22 of the pole pieces,the correct spacing ofthe latter isautomatically accomplished by attaching the plate 18.4 This plate also permitsl the handling of the4 two pole piecesas a single rigid unit.

y 0n thepolar extensions 1,2 is mounted a current-generating coil 23, which prefer-ably fits snugly between thesides 24 of the pole pieces and is thus firmly held in place without additional fastening means. If necessary, the casing C may be formed with a bulge 24 to accommodate the coil 23. 1t

` is understood, of course, that the coil 23 is inserted inrposition on the pole pieces before thesame are connected together by the. plate 18. The polar. extensions 12 consti- 1 tutena magnetic core for the coil 23, and

the airgap'13l is of such Width as to' provide `a magnetic path of predetermined reluctance.V Aswill be clear from Fig. 4, the polar j extensions .11 and 12 provide parallel mag- -are an electrical representation (as itjvere) transversely of the vcasing (from left to right as viewed in Fig. 2). To the inner end of needle arm 2T is attached a magnetic vibratory strip or armature 30. The ends of this strip 4are secured to a pair of nonl.magnetic brackets 31, as by screws 32 0r otherwise.I The brackets 31 are in this instance' secured to the polar lim-bs 11 by screws 33 entering screw-holes 34 in the pole pieces. 4The needle arm 27 is connected to the vibratory strip 3 0 at the center, so that the strip may vibrate symmetrically with respect to the polar faces 14.Y The magnetic strip is preferably made of resilient magnetic-4 metal, so that it may also act as an automatic restoring and centering spring for the/"needle arm. Normally, the vibratory strip or a-rmature 30 is separated from the polar faces 14 by a pair of'airgaps 35. Since these two airgaps are in series, they may be referred to as a single airgap of nornfially predetermined reluctance. erably, the reluctance of the shunt airgap 13 is made equal to the normal reluctance ofthe double airgap 35, so that the normal lield flux divides about evenly between the shunt path 12 and the mainpath including the polar limbs 11 and thc armatures 30;

lTo facilitate adjustmentof the relative reluctances of the airgaps 13 and 35, the normal distance of the arn'iature from the polail faces 14 may be regulatedin 'any practical way. For instance, `one or more shims can be interposed between the armature ends and the anges 31 ofrbrackets 31. Or, the fas- -tening screws 33 may engage in longitudinal slots in brackets 31, so as to permit adjustment of the latter' along the sides of the pole pieces.,

lThe operation of the constructionl above described will be clear to those skilled inthe art without further explanation, but I may brieiiy summarize it as follows: As the needle l arm vibrates under .the action of the recordplaying needle, the armature strip 30 is moved toward and away from the polar faces 14. lVhen the armature moves toward the pole pieces, the magnetic reluctance through the main path 11 is decreased, and therefore the greater port-ion of the field flux passes out' side the coil 23 through the polar extensions 11 and armature 30. r1`he next instant, when the armature 30 moves away from the polar faces 14, the flux through the shunt field 12.

is increased. Consequently, this variation of iux through the .coil`23 as the armature 30 'vibrates, causes current impulsesto be (T erated in the coil, and these-current impiisgs of the mechanical movements of the needle arm. Since the armature 30 is at r greater distance from the pivot, 26 o the needle arm than` is the' point of the record needle,V it is'clear that the needle vibrations a greatlyA are transmitted to the armature 1n ipljifhfhftlielts *Mimi-,iii friendliest l lle )ro duce sliltlicient 1 y v ultane'oasly gl tl e shunt aath 'and vicey t'ljf,"sli`gh`tw1h"' si'otthe f-"an increased iragneticx etn ieanimportantfaiture ofnfy in'entioi o nabl'es the elettrici-e# froduoti'on' "of records having )Several hun"- hrationsam very delieatefeven in L'their `mati- "m-mamplitude-I f l* i i f It is" hardly neeessary' to explainfthatjthe 4 ycoilQBi's Supposed to beeonneetetl ina suitable eireuitrfor operatingloudspeaker meehanisnil`- It" eeded`,"the current impulees in coil *235 may" Vhe anpliethf as 1 byy means ot' radio ttibesrsi1iiilar deVieeS, "bet-ore operat ing'or :Controlling ay loudspeaker. these yCircuiti` Connections j are well under-stood. I I need not'yshow* or describe Athem `iny ydetail. Itfi'ssuieientthatI shoW the ends lnofooil posts 37 o ntlie back pla'tel 'of theeasing. Circuit `-conduc't"ors 381ead f1-om! the bindingvpostsy :37 ytosuitable amplifying y'apparatus or lto fthefeleetomagnetio meehaniSm of a loudspeaker. By lconcealing th'ewconductors `38 Within the supporting' tube 75? the' neat-ness of the instrumentiefenhanced; JThe Tairgap. 13jin:tl1esh'unt path 12 need vnotgilneeesai'ily be arranged' Centrally offV the as' a fixedv airgapyIdoflnot meaxr thatdtis gap-ea 2 ving' arm.

23y Connected' to va` pair `of insulated binding 'y coniprismg a ymagnet rangedto provide a'nmgnetio Shunt patltconairga'p, i a'r coil mounted-z, 4vso as to 'be` vtot the `flux ymfsald shuntpath, andiga;y

p in a'llf'fcasesn Hadjlistalole,` but Iuse* thevterm i this'airgap-{fromfithe l v The f airgap y; ift-deiredg"beadjnstable' to i eoil ontsaicteore tliew'ibratioiisfo ber varyingthetmagnetiegi-L Core? to generate, eurrent'impulses 1 a: magnet ttucture'@having-ty ipole rangedi tot `rovil v two.: parallel z' paths `:"bfetwvee the magnet?, poles; so

phragm anyfother magnetico em e1.. vibration'. 'llhe` irepiiodneer ot ,fplzq n tiealie'ut records lepndf 1Smounted; onthe 1 .Byarranging the brac-liet 18 and the armature` or freed, 230: laterally ot maj. fnetr eutzui'ecolrds and ing on the way i't '.M, -tha.t is, E to one side thereotfgmakelit died linesfto thevl inch Wherejljthelneedlevvi#.

easier to. tix `the politi-inrit in plaeeand to `connect ythe armature with .they stylus; holder.

he mechanically: carried outlinother forms than herein Set forth Without `departing from the seopeo'iwthe appended 'claime 1 `XVhat'I `clain'iz asv my intention-is;

l: An eleetriefdeviee of the class described. having 2 pole pieces vartn liningv an a1rgap,y said kpole pieeesy` having polar iacesf arrangedwto orm 1an Oplaftive- 4bie/Ct" tory magnetic`y member mounted 1n` operative `relatioirt-o saidpole faces toy vary saidlaet mentioned airgapefor` controllingthe magn'etiez flux passingcthiough saidJ i shunt; path t and said coil," said memben bei-ng adapted i to be'acoustically actuatedl y t i 52; In fan electricy devicep`` i i elasksv fseril'ie'd,` af magnethaving apairaofrpole vpieces,

a vibratory magnetiememloerA mountejdi `in` opera'tivek relation,tothe;y polar faces i of 1 said pole p1eees,la .pairioffaxialfly ahgnedextenslons on rSaid i pole@pieeesaA said extensions being? 1sepa `rated'byanaalrg'avpand eonstltutmg a magnetle .core of ff predetermined Hreluetance t is 3. In afnffeleetrephonographrreprodueer,

bratory magnetic strip mounted in oper-n through said vibratory member does not pass through the path containing said coil, and a needle arm connected to said member.

et. An electric device of the class described comprising a magnet having pole pieces arranged to provide a magnetic shunt path containing an airgap, a coil mounted so as to be subject to the iiux in said shunt path, a vi core, and a needle arm forv vibrating said strip' in amplified relation to the' needle vibrations, the vibrations of said strip varying the magnetic fiuxthrough said shunt path to generate current impulses in said coil.

6. In an electric device of vthe class described, a magnet having pole pieces con-y structed to provide two parallel p aths for the magnetic fiux, one of said paths having a fixed airgap and the other path having a variable airgap, a vibratory magnetic member operatively associated Vwith said pole pieces andincluded in the secondmentioned path, said airvgaps being so proportioned that normally said paths have practically the same magnetic reluctance, and a Acoil arrangedmto 'be traversed by the flux in the first-mentioned path,

. said magnetic member beingA acoustically actuated to vary the reluctance of the secondmentioned magnetic path and therebye vary the fiux through said coil.

7. An i -ielectric phonograph reproducer comprising a magnet structure adapted to provide two parallel magnetic paths between the magnet poles, apath containing a fixed airgap and a coil, the \other path including a vibratory magnetic member arranged to provide a variable airgap in said otlir path, so that vibrations of said member vary the magnetic iiux through said coil, and a needle arm connected at its inner end to said member for transmitting thereto 'the needle vibrations in amplified ratio.

8. In an electric device of the class de- Y scribed, a magnet having pole pieces providedV each WithvtWo extensions, one pair of opposite extensions terminating in aligned polar faces,

- the second pair of extensions vprojecting to- Ward each other in axial alignment and being separated by a fixed airgap, said second pair of nolar extensions forming a magnetic shunt path, a coilon 4said shunt extensions, and a vibratory magnetic member operatively associated with said polar faces to vary the magnetic flux through said shunt path and said coil. l

9. In an. electric phonograph reproducer, a casing adapted to be mounted on a suit-I able support, a magnet in said casing, said magnet having pole pieces provided each WithV two extensions, one pair of opposite extensions `terminating in aligned polar faces, the second pair of extensions projecting toward each other in axial alignment and being separated by a fixed airgap, said second pair of polarextensions forming a magnetic shunt path, a coil on said shunt extensions, a vibratory magnetic member operatively associated with said polar faces to vary the Vmagnetic flux through said shunt path and said coil, and a needlearm connected at its inner end to the Center of said strip for actuating the same in ampli-- fied relation -tothe needle vibrations, said strip act-ing as a centralizing and restoring spring for the needle arm.

l0. In an electric device of the class described, electromagnetic current-generatinQF mechanism including a resilient magnetic strip supported for .vibratory movement, a non-resilient vibratory member Yconnected to said strip for actuating the same, said resilient vstrip also serving as a restoring spring for said member, and acoustic means for op-` erating said member.

. 1l. In an electricy device of the class described, a magnet having a p air of pole pieces attached to the polar ends of the magnet, a non-magnetic plate for securing said pole piecesl together in properly spaced relation independently of said magnet, a pair of nonmagnetic brackets attached to said pole pieces, a vibratory magnetic strip secured atitsends to said brackets and arranged in operative relation to the polar faces of said polepieces, a pair of axially aligned extensions on sai ing a magnetic core of predetermined reluctance, a coil on said core, and means for vibrating said magnetic strip.

l2. In an electric device of the class described, a magnet having pole pieces provided each With -tWo extensions, one pair ofvopposite extensions terminating in aligned polarv faces, a non-magnetic plate to Which said lastnamed extensions are secured in properly spaced relation, so that saidA pole pieces'are rigidly connected as a unit independently of the magnet, the second pair of extensions projecting toward each other'in axial alignment and beingseparated by an airgap, said second pair of polar extensions forming a magnetic .shunt path of predetermined reluctance, a coil on said shunt extensions, a pair ofL non-magnetic brackets secured to said first-mentioned polarextensions, a vibratory magnetic strip attached at its ends to said brackets and arranged in operative relation to said polar Dole pieces, said extensions being separatedAA by an'alrgap and comprlsop@ elution tionedat a distance frolnthe'plane' of said "nj1agnet,""so `f that 4 the" connection between said stylus Holder and armature 'passes outside 'of saicllnagnetandpole pieces.` g

14;" kkAn electromagnetic `phonograph `pickl separate ilpole pieces, va `Coil y"rnojilnted vbetween "said "pole pieces", a non-magnetic' plate air- 'ranged transverselyof saidfmagnetto neside means Vfor securing said :plate to said 'pole piecesto hold Athe saine and said 'coilin prop# "'.erly spaced` relation as fa' :single `rigid unit, a

""t'fibratlory yInaenetief reed I'n'ol'u'ltedl` on" said unit `a`s"part thereof in `operative relation to 's'si'dfcoil and"p'(Jlewpieces,L theinou'nting of said "reed being silehthat `it is resiliently held yin predetermined `norrna-1`fpositit'm with rey saidlynnit to said magnet,` and 'af stylushold'er 4c'oyuieeted to f'said' reed andpositioned" `at a distancefrm; tlie'planebf said Inagfnetg` so and pele pieces f" comprising; 'al magnet; 'al pairl ofi separate es". acoil nounted"betweeni'saidfpole said vluding is' "d 'f' nating in aligned n'iagneticmembr ign Y: pole faeeglneans to rovgii fof* predetermined "hlder 'connectedltosaic armature and `posi--v therei"andA o'verlappingfsaid Apole `pieces," Y y y y extending betweensaid" pole pieces and proi* 19; An" electric phonograph; reprodufed comprising a` imagine@ a--vibratory armature `electrically',affeeteiil y the vibrationssof'-` said.

'armature strip5` Whiclialso antsy asa centering-1! y p *y restoring springfforsaidfneedle'arm.

Styls holder; passes `outside offsad magnet f1 "tl'iroud "onepathandisinnlltaneouslyincrease tensions v :zslbje @tance between `Seid xpolewpiecesindependently of said v-ibratory mennber; and a. coilf, inv said patli-,y said vibra- `tory nieniberfand said coil heilig so arranged'.

.i thatf the magnetioxfhlfx passing through' said "member does not pass through the `pathccmltainingsaidcoil. yY Y V y i 1 8, yIn an electri fdeyiceof the classde- 85 scribed, a magnet liaying pole pieces arranged i toforinan .operatiy'e airgap, a Vibratory' magnetio Inelnber magnetically separated from said pole pieces and spanning the spacev theref between to vary said.airg"ap,- allmagneticfcore aidingl a `predeterniined airgap independently ofsad membenanda vcoil yonfsaijd come.

operatively associated `withl said magnetil said mature consisting faresilient stripsuppoljtedf-at' its ends, `da needle arm: Connected to `th Center of"Saidresilienty strip, and af-coil Inlan elet-rio'ljhonograph reproducer, amagnet havin-g `pole 4 p1e`ces'te-'rminating 1n i in operatlve relation said pole. nieces,

mounting of'isaid'reed 4being-such that it is resiliently held in predeterniin'ed .norinal pofor attaching said unit to said magnet, and a 'stylus holder connected to said reed and positioned ata distance from the planejofsaid magnet, sov that the connection between said-- reed and stylus holderpasses outside of said E magnet end polepieces.

22; An electromagnetic phonograph pickup conprising a magnet, a'pair of pole pieces extending laterally of said magnet, a coil mounted 'between' said pole pieces, av single non-magnetic bracket havinr a straight fiat section secured to vone face otsaid pole pieces for rigidly'holding vthe same vand said coil in lproperly spaeedrelationas a unit, said bracket extending transversely ofsaid mag net'and to one side thereof, an armature, means for mounting'saidarmature on said unit as part thereof, means for attaching said unit kto said magnet, and a stylus holder connected to said armature.

screw means for securing said u nit with its armature and coil to .said magnet. and a' stylus holder connected to said armature and proi eating from said easing. said'stylus holder vbeing positioned to one side o f-the' plane 'of said magnet. v

24. An 'electromagnetic ,pick-un device I comprising bracket means ,forl SIJDDOrting polej'pieces and a magnetic reed in cooperative relatin to each other. said bracket means and the parts supported therebytconstituting a unitary structure, a magnet and Vmeans for rigidly securingc the unitary strue'tireaforesa id to said'magnet with the pole pieces properly related to the Doles of the'-magnet and nected withthe permanent :magnet-'and the reed is then movably related-tn sjaid y:u'nmovably held pole pieces. saidi'blaoket-means being arranged to oneside ofsaidfmagnet.

25. In an electromagneticpickup having a magnet, a unitarsr structureattached to the polar ends of Sadmagnet-,saiduntary strue- .ture comprising pole pieces. a. coiland anarmature, said parts being Aheld inoperative relation by rigid non-magnetic Ineans Itorming part of said unitary structure, and astylus, oldel connected to' said armature, said unitary structure and stylus holder being arranged to one side of the' plane of said magnet.- sition/With respect tojsaid pole pieces. means 26. An electromagnetic pickup comprising a magnet, polepieees for said magnet, nonmagnetic means arranged laterally of said magnet for connecting said pole pieces in properly 'spaced relation as a. rigid unit, a/eoil operatively associated with'said pole pieces,

a Avibratory armature, means for mounting said armature on said/unit, .means for attaching said unit to said magnet, and a stylus ,holder connected to said armature and .positioned to one side of the plane of said magnet. 27. In .an electromagnetic device of the class described, the combination of a magnet,

a pair of. pole pieces, a coil operatively asso- Vc1ated,\v1th sald pole pieces, non-magnetic means positioned laterally of said magnet for spaced relation as a single rigid unit,- a visecurnigsaid pole pieces andcoil in properly bratory armature, means for `mounting said.

armature-on said unit in operative relation to said p ole pieces, means for attaching said unit to said magnet. and a stylus holder connected to-said armature and positioned to one side of the plane of said magnet.

28. An electromagneticpickup comprising a magnet, pole pieces for said magnet, nonmagnetic means for connecting said pole pieces in properly spaced elationas a rigid unit, a coil operatively associated with said pole pieces, a vibratory armature, means for mounting said armature on said unit laterally of said'magnet, means for attaching said unit to said magnet, means for adJusting the normal relation between said armature and pole pieces, and astylus holder connected to saidarmature and positioned to one side of the' planeet said magnet.

29. An electromagnetic phonograph pieki up comprising a magnet, a pair of pole pieces,

a single non-magnetic bracket connected to both pole pieces for securing them in properly spacedrelation, said bracket'and pole pieces constituting a rigid unit, a coil mounted on vsaid unit, a vibratory armature, means for mounting said armature on said unit as part thereof, means for securing said unit to said ma et, said armature being positioned latera ly of said magnet, and a stylus holder for operating said armature. whereby said pole piecesare lmmovablyeon- 30. In an electromagnetlc pickup, the combination of a U-shaped permanentmagnet, a pair of pole pieces, a non-magnetic bracket, screw means for securing said pole pieces to said bracket in properly spaced relation, an

amature and coil operatively associated wit-h said er with said armature and coil constituting a'. single unitstructure, means for attaching-said unit structure to said magnet in p ole pieces, said bracket and pole pieces toget 'such position that said bracket and armature are arranged laterally of said magnet; a stylus .holder ipositioned at v'a distance from; the planeo `said magnet, and a rigldconnection between said armature and stylus holder, said connection passing outside of said magnet and pole pieces. j

3l. An electromagnetic pickup comprising a magnet, a bracket, pole pieces secured to said "bracket in properly spaced relation, whereby said bracket and pole pieces constitute a unitary structure projecting laterally of said magnet, an armature and coil operatively mounted on said structure, means for securing said structure and the parts carried thereby to said magnet'with the pole pieces properl)7 related to the poles of the magnet,

means for adjusting the normal position of said armature with respect to the pole pieces,

a stylus holder positioned at a dista-nee fromVIV the plane of said mag rnet,-and a rigid connection between said. armature and said stylus holder, said connection passing outside of said magnet and pole pieces.

32. An electromagnetic pickup comprising a substantially Ushaped magnet, pole pieces having a pair of opposed projections arranged to provide an ail-gap and a. second pair of opposed projections more Widely separated, a bridge piece overlying the lastnamed projections and secured thereto. said bridge piece being arranged laterally of said magnet and With-said pole pieces constituting a single rigid unit, an armature and coil operatively mounted on said unit, means foe-se- 'curingr said unit to the legs of said magnet, a

stylus holder positioned at a distaneefrom the plane of said magnet, and a rigid connection between said armature and saidstylus holder, said connection passing outside of said magnet and polepieces.

33. An electromagnetic device adapted for conversion of energies for the reproduction of sound, comprising a permanent magnet having poles, a unitary assembly detaehably y associated with said magnet at the poles thereof and comprising polar shoes, at least one coll mounted on said shoes, anarmature vibratably associated with said coil andA shoes, saids varmature being arranged outside ofsaid coil, and an actuating means asso-` ciated with said armature for transmission of vibrations to or from the same.

ADoLPH- .virHoMAs. 

